The invention relates to presenting images to an observer.
Advertising images, for example, are sometimes presented on a grid of lights that are turned on or off in patterns. Such images can be made to appear to move, for example, in the manner used on the well-known traveling-message sign in Times Square in New York.
Others have suggested altering such a sign by decimating selected columns of the lights. The moving text could then still be perceived if the speed of motion of the text were chosen correctly. On such a decimated display, an observer would see either flickering, stationary columns or the moving text, depending on whether the observer's gaze were fixed or were tracking the moving text.
In a similar way, an observer can perceive the complete image of a large sign on a truck that is moving behind a picket fence even though only portions of the sign are visible at any moment. The persistency capability of human vision that enables the observer to perceive the message.